javax.activation.FileTypeMap Maven / Gradle / Ivy
/*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
*
* Copyright (c) 1997-2017 Oracle and/or its affiliates. All rights reserved.
*
* The contents of this file are subject to the terms of either the GNU
* General Public License Version 2 only ("GPL") or the Common Development
* and Distribution License("CDDL") (collectively, the "License"). You
* may not use this file except in compliance with the License. You can
* obtain a copy of the License at
* https://oss.oracle.com/licenses/CDDL+GPL-1.1
* or LICENSE.txt. See the License for the specific
* language governing permissions and limitations under the License.
*
* When distributing the software, include this License Header Notice in each
* file and include the License file at LICENSE.txt.
*
* GPL Classpath Exception:
* Oracle designates this particular file as subject to the "Classpath"
* exception as provided by Oracle in the GPL Version 2 section of the License
* file that accompanied this code.
*
* Modifications:
* If applicable, add the following below the License Header, with the fields
* enclosed by brackets [] replaced by your own identifying information:
* "Portions Copyright [year] [name of copyright owner]"
*
* Contributor(s):
* If you wish your version of this file to be governed by only the CDDL or
* only the GPL Version 2, indicate your decision by adding "[Contributor]
* elects to include this software in this distribution under the [CDDL or GPL
* Version 2] license." If you don't indicate a single choice of license, a
* recipient has the option to distribute your version of this file under
* either the CDDL, the GPL Version 2 or to extend the choice of license to
* its licensees as provided above. However, if you add GPL Version 2 code
* and therefore, elected the GPL Version 2 license, then the option applies
* only if the new code is made subject to such option by the copyright
* holder.
*/
package javax.activation;
import java.io.File;
import java.util.Map;
import java.util.WeakHashMap;
/**
* The FileTypeMap is an abstract class that provides a data typing
* interface for files. Implementations of this class will
* implement the getContentType methods which will derive a content
* type from a file name or a File object. FileTypeMaps could use any
* scheme to determine the data type, from examining the file extension
* of a file (like the MimetypesFileTypeMap) to opening the file and
* trying to derive its type from the contents of the file. The
* FileDataSource class uses the default FileTypeMap (a MimetypesFileTypeMap
* unless changed) to determine the content type of files.
*
* @see javax.activation.FileTypeMap
* @see javax.activation.FileDataSource
* @see javax.activation.MimetypesFileTypeMap
*/
public abstract class FileTypeMap {
private static FileTypeMap defaultMap = null;
private static Map map =
new WeakHashMap();
/**
* The default constructor.
*/
public FileTypeMap() {
super();
}
/**
* Return the type of the file object. This method should
* always return a valid MIME type.
*
* @param file A file to be typed.
* @return The content type.
*/
abstract public String getContentType(File file);
/**
* Return the type of the file passed in. This method should
* always return a valid MIME type.
*
* @param filename the pathname of the file.
* @return The content type.
*/
abstract public String getContentType(String filename);
/**
* Sets the default FileTypeMap for the system. This instance
* will be returned to callers of getDefaultFileTypeMap.
*
* @param fileTypeMap The FileTypeMap.
* @exception SecurityException if the caller doesn't have permission
* to change the default
*/
public static synchronized void setDefaultFileTypeMap(FileTypeMap fileTypeMap) {
SecurityManager security = System.getSecurityManager();
if (security != null) {
try {
// if it's ok with the SecurityManager, it's ok with me...
security.checkSetFactory();
} catch (SecurityException ex) {
// otherwise, we also allow it if this code and the
// factory come from the same (non-system) class loader (e.g.,
// the JAF classes were loaded with the applet classes).
ClassLoader cl = FileTypeMap.class.getClassLoader();
if (cl == null || cl.getParent() == null ||
cl != fileTypeMap.getClass().getClassLoader())
throw ex;
}
}
// remove any per-thread-context-class-loader FileTypeMap
map.remove(SecuritySupport.getContextClassLoader());
defaultMap = fileTypeMap;
}
/**
* Return the default FileTypeMap for the system.
* If setDefaultFileTypeMap was called, return
* that instance, otherwise return an instance of
* MimetypesFileTypeMap.
*
* @return The default FileTypeMap
* @see javax.activation.FileTypeMap#setDefaultFileTypeMap
*/
public static synchronized FileTypeMap getDefaultFileTypeMap() {
if (defaultMap != null)
return defaultMap;
// fetch per-thread-context-class-loader default
ClassLoader tccl = SecuritySupport.getContextClassLoader();
FileTypeMap def = map.get(tccl);
if (def == null) {
def = new MimetypesFileTypeMap();
map.put(tccl, def);
}
return def;
}
}